1. Field of the Invention
The invention relates to a mounting assembly for an exhaust gas catalyst, including a metallic catalyst carrier body and a tubular jacket in which the catalyst carrier body is embedded.
2. Description of the Related Art
Metallic exhaust gas catalyst carrier bodies are known, for instance, from German Published, Non-Prosecuted Applications DE-OS 29 24 592 and DE-OS 33 12 944, the latter being in a more developed form. Such exhaust gas catalyst carrier bodies are coated with a catalyst material which causes the decontamination of exhaust gases. In the operating state, the catalyst carrier bodies are subjected over long periods of time to high temperatures and to alternating stresses. In addition, they must be made of high-temperature resistant steel alloys which are only slightly corrosion-prone.
During the installation of such catalyst carrier bodies in the exhaust gas systems of motor vehicles, the mounting of the bodies presents a particular problem The catalyst carrier bodies must be installed in a strong housing, such as a tubular jacket and furthermore they have to be thermally insulated. Problems arise in this connection, since the carrier bodies are subjected to expansion particularly in the longitudinal direction, at high temperatures and with increasing operating times.
If this expansion is impeded, such as by firm connections with a tubular jacket in more than one zone along the axial length, this leads to a progressive destruction of the jacket zone of the carrier body until it separates from the jacket. In addition, the otherwise good start-up behavior of a catalyst with a metallic carrier body is deteriorated if the thick tubular jacket must first be heated up concurrently during the starting phase.